raptor (RDF Parser & Serializer)

Raptor is a free software/Open Source C library that provides a set of
parsers and serializers that generate Resource Description Framework
(RDF) triples by parsing syntaxes or serialize the triples into a
syntax.  The supported parsing syntaxes are RDF/XML, N-Triples, TRiG,
Turtle, RSS tag soup including all versions of RSS, Atom 1.0 and 0.3,
GRDDL and microformats for HTML, XHTML and XML.